Mechanized retractable pellicles and methods of use

ABSTRACT

Apparatus and methods to protect a photomask that is used for semiconductor photolithography at wavelengths outside the visible spectrum include a pellicle that is readily retracted during exposure or to provide access to the photomask. The pellicle can be transparent at an inspection wavelength and opaque at an exposure wavelength. In various embodiments, the pellicle is slid, retracted, or pivoted relative to a base aligned with the photomask, thus uncovering the photomask. When overlying the photomask, the pellicle can be secured with magnetic elements, such as magnets or electromagnets. In another embodiment, the pellicle includes a diaphragm having a plurality of shutter leaves that can be opened or closed. Methods of using a pellicle are also described.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.09/840,364, filed Apr. 23, 2001, now issued as U.S. Pat. No. 6,734,445,which is incorporated herein by reference.

The inventive subject matter is also related to the followingapplications that are assigned to the same assignee as the presentapplication:

Ser. No. 09/840,373, entitled “Hinged Pellicles and Methods of Use”, nowU.S. Pat. No. 6,569,582; and

Ser. No. 09/840,407, entitled “Dual-Member Pellicle Assemblies andMethods of Use”, now U.S. Pat. No. 6,566,018.

TECHNICAL FIELD

The inventive subject matter relates generally to the field ofsemiconductors and, more particularly, to a mechanized retractablepellicle that can be retracted to uncover a photomask and to methods ofuse.

BACKGROUND INFORMATION

In semiconductor processing, a photolithographic mask (photomask) isused to pattern a radiation sensitive layer on a semiconductorsubstrate. Typically, the radiation sensitive layer is called aphotoresist layer. A “photomask” is defined herein as the combination ofa base and a patterning material. Typically, the base comprises a quartzor glass plate, which is transparent to the exposing radiation, and thepatterning material lies on one side of the quartz plate and typicallycomprises chrome, aluminum, or gold, which is opaque to the exposingradiation. A stepping field is the portion of the patterning materialthat is used to pattern the photoresist layer.

The photoresist layer is sensitive to photomask defects, such asparticles, for example. If a particle is present on a photomask withinthe stepping field when a photoresist layer is exposed using thephotomask, the particle may cause a corresponding image to be formed inthe patterned photoresist layer, which in turn may cause the devicebeing fabricated to fail. If the stepping field of the photomaskcontains only one die, then all die that are fabricated on thesemiconductor substrate could fail.

A pellicle is typically used to reduce the likelihood that particlesmigrate onto the stepping field of a photomask. A “pellicle” is definedherein to include a pellicle frame and a pellicle membrane. The pelliclemembrane is typically a thin, flat, usually organic material, such asnitrocellulose or cellulose acetate, and it may be coated with one ormore layers of fluoropolymers.

FIG. 1 illustrates a perspective view of prior art semiconductorphotolithography equipment 1, including a prior art pellicle. Theequipment 1 includes an illumination optical system 2, including asource 4 of photolithographic radiation 6. The equipment 1 furtherincludes a photomask substrate 10 having on its upper surface 12 aphotoresist or photolithographic pattern 14. The photomask comprisessubstrate 10 and photolithographic pattern 14.

To protect the photomask, a pellicle comprising pellicle frame 16 andpellicle membrane 20 is positioned a certain distance over thephotomask. Pellicle frame 16 is typically a single-walled frame ofmetal, metal alloy, or plastic. Pellicle membrane 20 is typicallyfastened to pellicle frame 16 via an adhesive or adhesive tape (notshown).

A pellicle can protect a photomask from particles existing within thephotolithography area. Photolithography is done in an ambientenvironment where particles are present, even in the cleanest ofclean-room environments. Cleaning particles from the photomask can bedifficult because of the relatively tight spacing between the photomaskand the pellicle membrane. To properly clean a photomask and itspellicle often requires that they be removed from the photolithographyarea to a mask shop for several hours or even several days, at asignificant expenditure of production resources. This can delay theproduction of semiconductors.

Therefore, there is a significant need for a pellicle that can bereadily removed and replaced to facilitate cleaning of the photomask andpellicle membrane.

Further, the line dimensions of semiconductor devices are constantlyshrinking. In order to achieve smaller patterning dimensions,photolithography must be carried out at increasingly shorterwavelengths. However, organic pellicle membranes cannot be used forshorter wavelengths. Radiation at such wavelengths is referred to asactinic, in that it can cause a chemical reaction in or near thepellicle membranes, causing them to deteriorate. For example, atapproximately 200 nanometers (nm) and below a reaction occurs betweenthe radiation and the air between the photomask and the pelliclemembrane, producing ozone that breaks down an organic pellicle membrane.In some instances, the pellicle membrane becomes damaged during only oneexposure to actinic radiation. In addition, at very short wavelengths,an organic pellicle is not transparent to the photolithographicradiation, because the pellicle has very high absorption at thesewavelengths.

For the reasons stated above, and for other reasons stated below whichwill become apparent to those skilled in the art upon reading andunderstanding the present specification, there is a significant need inthe art for a pellicle device that adequately protects a photomask, andthat does not deteriorate when the photomask is being exposed, as wellas for methods of operating such a pellicle device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a perspective view of prior art semiconductorphotolithography equipment, including a prior art pellicle;

FIG. 2 illustrates a partially exploded perspective view ofphotolithographic equipment in accordance with one embodiment of theinvention;

FIG. 3 illustrates a partially exploded frontal view of thephotolithographic equipment of FIG. 2;

FIG. 4 illustrates a partially exploded frontal view of anotherembodiment of photolithographic equipment;

FIG. 5 illustrates a partially exploded frontal view of yet anotherembodiment of photolithographic equipment;

FIG. 6 illustrates a partially exploded side view of the embodiment ofphotolithographic equipment illustrated in FIG. 5;

FIG. 7 illustrates a partially exploded perspective view ofphotolithographic equipment in accordance with one embodiment of theinvention;

FIG. 8 illustrates a top view of the embodiment of photolithographicequipment illustrated in FIG. 7;

FIG. 9 illustrates a perspective view of photolithographic equipment inaccordance with one embodiment of the invention;

FIG. 10 illustrates a cross-sectional view of the photolithographicequipment illustrated in FIG. 9 taken along line 201 of FIG. 9.

FIG. 11 illustrates a perspective view of photolithographic equipment inaccordance with one embodiment of the invention;

FIG. 12 illustrates a cross-sectional view of the photolithographicequipment illustrated in FIG. 11 taken along line 301 of FIG. 11.

FIG. 13 illustrates a perspective view of photolithographic equipment inaccordance with one embodiment of the invention;

FIG. 14 illustrates a cross-sectional view of photolithographicequipment 400 taken along line 401 of FIG. 13.

FIG. 15 illustrates a flow diagram of a method of using a retractablepellicle, in accordance with one embodiment of the invention;

FIG. 16 illustrates a flow diagram of a method of using a pivotablepellicle, in accordance with one embodiment of the invention;

FIG. 17 illustrates a flow diagram of a method of using a pelliclecomprising two or more shutters, in accordance with one embodiment ofthe invention; and

FIG. 18 illustrates a flow diagram of a method of using a pelliclecomprising a diaphragm, in accordance with one embodiment of theinvention.

DETAILED DESCRIPTION

In the following detailed description of embodiments of the invention,reference is made to the accompanying drawings which form a part hereof,and in which is shown by way of illustration specific preferredembodiments in which the inventive subject matter may be practiced.These embodiments are described in sufficient detail to enable thoseskilled in the art to practice the invention, and it is to be understoodthat other embodiments may be utilized and that architectural, optical,compositional, mechanical, and electrical changes may be made withoutdeparting from the spirit and scope of the inventive subject matter.Such embodiments of the inventive subject matter may be referred to,individually and/or collectively, herein by the term “invention” merelyfor convenience and without intending to voluntarily limit the scope ofthis application to any single invention or inventive concept if morethan one is in fact disclosed. The following detailed description is,therefore, not to be taken in a limiting sense, and the scope of thepresent invention is defined only by the appended claims.

The present invention provides a solution to the problem of providingready access to a photomask that is protected by a pellicle, and to theproblem of pellicle membrane deterioration to radiation beyond thevisible light spectrum, such as ultraviolet, deep ultraviolet, extremeultraviolet, X-ray, electron beam, ion beam, and the like. The rangebeing used and being evaluated by current semiconductor photolithographyis in the range of 2 to 200 nm, but the invention is not limited to suchrange.

Various embodiments are illustrated and described herein. Generally, apellicle overlying a photomask can be retracted to uncover thephotomask. In one embodiment, the pellicle frame is slid relative to thephotomask to permit the photomask to be accessed or to be exposed tophotolithographic radiation, and the pellicle frame is slid back tocover the photomask when it is not being accessed or exposed tophotolithographic radiation. In another embodiment, the pellicle framecomprises two or more shutters to move relative to the base between afirst position overlying the photomask and a second position notoverlying the photomask to expose the photomask to a source ofphotolithographic radiation. In a further embodiment, the pellicle framecan be pivoted about a vertical axis relative to the base to expose orcover the photomask, respectively. In yet another embodiment, thepellicle frame comprises a diaphragm that opens to expose the photomask.To secure the pellicle frame and the base in alignment, varioustechniques can be used, including the use of magnetic force andmechanical clamping. Various methods of using a pellicle are alsodescribed.

The present invention, as implemented in various embodiments, providesprotection of photomasks that are subjected to actinic radiation at theexposure wavelengths mentioned earlier. For photolithographic exposureusing either actinic or non-actinic radiation, it provides ready accessto the photomask for cleaning, inspection, adjustment, removal,replacement, or other purposes.

FIG. 2 illustrates a partially exploded perspective view ofphotolithographic equipment 30 in accordance with one embodiment of theinvention. The equipment 30 can include an illumination optical system(not shown) like that illustrated in FIG. 1. The equipment 30 furtherincludes a photomask base 32 that supports a photomask 34 comprising aphotolithographic pattern 36.

A pellicle 50 is suitably coupled to a pellicle frame 40, e.g. by usingan adhesive element such as an adhesive or adhesive tape. The adhesiveelement is preferably non-outgassing and non-particulating. Pellicleframe 40 comprises a pair of arm members or arms 82 and 84 that arecoupled to a transport rod 80. While two arms 82 and 84 are illustratedin FIG. 2, in other embodiments more or fewer arms could be used.Although arms 82 and 84 are shown coupled to a long dimension ofpellicle frame 40, they could alternatively be coupled to a shorterdimension of pellicle frame 40.

Transport rod 80 is controlled by transport elements or units 60 and 70.Transport units 60 and 70 comprise suitable mechanical,electromechanical, and/or electronic elements to control the desiredmovement of pellicle frame 40. One of ordinary skill in the art candesign and implement suitable transport units 60 and 70, depending uponthe requirements of the particular photolithography equipment. Transportrod 80 could comprise a threaded rod to mate with corresponding threadedholes in arms 82 and 84, so that the rotation of transport rod 80 couldmove pellicle frame 40 in the directions indicated by dashed arrow 92,to either move pellicle 50 to a first position overlying photomask 34 orto move pellicle 50 to a second position not overlying photomask 34 toallow photomask 34 to be accessed (e.g. for cleaning or replacementpurposes) or to be irradiated by photolithographic radiation. Othertypes of transport mechanisms could also be used.

If it is desired to secure pellicle frame 40 with respect to photomask34, optional photomask frame 38 can be provided. Photomask frame 38comprises a suitable securing mechanism to keep pellicle frame 40 andphotomask 34 in alignment. For example, a magnetic force can be used inthe form of permanent magnets 35 on the corners of photomask frame 38 tomate with corresponding magnets 45 of opposite magnetic polarity locatedon the corners of pellicle frame 40. Magnets, such as magnets 35 and 45,could be located anywhere on pellicle frame 40 and photomask frame 38,such as the corners and/or sides.

While the embodiment shown in FIG. 2 implements a securing mechanismthrough magnetic fields provided by permanent magnets such as magnets 35and 45, other suitable securing mechanisms could also be used, such asone or more electromagnets. Also, while the embodiment shown in FIG. 2places magnets 35 and 45 in photomask frame 38, in another embodimentthey could be positioned within photomask base 32, and photomask frame38 could be eliminated.

In yet another embodiment, a securing mechanism can be implementedthrough the use of mechanical clamps or other mechanical elements tomaintain the pellicle frame in alignment with the photomask. A robot orother form of electromechanical device can be utilized to release thesecuring mechanism to permit the pellicle frame to be moved away fromthe photomask.

Pellicle 50 is thus movable relative to the photomask 34, and it can beremoved from the path of photolithographic radiation by pivotlesslysliding or retracting it in the direction of transport unit 70. Pellicle50 is movable between a first position in which pellicle 50 overlies thephotomask base 32 and the photomask 34, and a second position whereinpellicle 50 does not overlie photomask 34.

Although photomask base 32 is depicted as relatively thick, it could beonly the thickness of the substrate of photomask 34. Alternatively,photomask base 32 can comprise other photolithography equipment inaddition to photomask 34. For example, photomask base 32 could comprisea photomask stage for moving or stepping photomask 34 in order toproject an image of photolithographic pattern 36 upon a wafer.

Although photomask base 32 is depicted in FIG. 2 as physicallysupporting photomask 34, the present invention is not limited to such anarrangement. Photomask base 32, for example, could be aligned with butnot supporting photomask 34.

Pellicle 50 is formed of a non-particulating material, such as a metal,metal alloy, plastic, quartz, silica glass, plexiglass, a polymericfilm, or other suitable material.

Pellicle 50 can be opaque, transparent, or can comprise a combination ofopaque and transparent portions. The terms “opaque” and “transparent”can be relative to either or both the exposure wavelength and aninspection wavelength. Typically an inspection wavelength is in thevisible spectrum, but for the present invention it is not limited to thevisible spectrum.

In one embodiment, pellicle 50 comprises a transparent portion (notshown) that is commensurate in size with photomask pattern 36. In suchembodiment, pellicle 50 is kept in place during inspection using visibleradiation, but pellicle 50 is removed during exposure tophotolithographic radiation.

In one embodiment, pellicle 50 covers the entire photomask 34.Alternatively, it can cover just the photomask pattern 36.

It will be understood that in FIG. 2 pellicle 50, pellicle frame 40,optional photomask frame 38, photomask 34, and photomask base 32 areillustrated in exploded form, and that in use pellicle 50 will be incontact with pellicle frame 40, photomask 34 will be in contact withphotomask base 32, and optional photomask frame 38 will be in contactwith photomask base 32.

When pellicle 50 is either in a first position overlying photomask 34 orin a second position away from and not overlying photomask 34, pellicle34 and pellicle frame 40 can be constructed in such a manner thatphysical contact is maintained between pellicle 50 and one or moreelements of its attendant structure (such as pellicle frame 40) andphotomask 34 and one or more elements of its attendant structure (suchas photomask base 32 and photomask frame 38).

When pellicle 50 is in the first position, the various elements makingup the pellicle device, namely photomask base 32, optional photomaskframe 38, pellicle frame 40, and pellicle 50, together form a protectiveenclosure around photomask 34 to protect photomask 34 from sources ofcontaminants such as particles. While such elements generally form amore protective enclosure if pellicle 50 and its attendant structure arein physical contact with photomask 34 and its attendant structure, theinvention does not require that such elements be in physical contact.

When pellicle 50 is in the second position, it is unnecessary forpellicle 50 and its attendant structure to remain in physical contactwith photomask 34 and its attendant structure. However, if desired,pellicle 50 and its attendant structure can remain in physical contactwith photomask 34 and its attendant structure, provided that photomask34 is sufficiently uncovered to allow exposure or access for aparticular purpose, such as cleaning.

FIG. 3 illustrates a partially exploded frontal view of thephotolithographic equipment 30 of FIG. 2. Pellicle 50 overlies and issecured to pellicle frame 40. Photomask 34 is not seen in FIG. 3, but itoverlies and is secured to photomask base 32. Optional photomask frame38 also overlies and is secured to photomask base 32. Optional photomaskframe 38 comprises magnets 35 on or near its upper surface to mate withcorresponding magnets 45 on or near the lower surface of pellicle frame40.

One end of arm 82 is coupled to pellicle frame 40, while the other endis coupled to transport rod 80, which is coupled between transport unit60 and transport unit 70 (not shown in FIG. 3).

FIG. 4 illustrates a partially exploded frontal view of anotherembodiment of photolithographic equipment. In this embodiment, one ormore electromagnets or solenoids have been substituted for one or morepermanent magnets in the embodiment illustrated in FIG. 3. For example,in FIG. 4 electromagnets 37 have been substituted for permanent magnets35 shown in FIG. 3. Electromagnets 37 can be coupled by an internalpower cord 39. Electromagnets 37 are coupled via a flexible externalpower cord 41 to electromagnet control unit 81 of transport unit 60.Electromagnet control unit 81 switches on electromagnets 37 whenpellicle frame 40 is overlying photomask base 32 to maintain pellicle 50over photomask base 32. When pellicle frame 40 is to be moved away fromphotomask base 32, electromagnet control unit 81 switches offelectromagnets 37.

While the embodiment shown in FIG. 4 illustrates electromagnets pairedwith permanent magnets, ferromagnetic material could be substituted forpermanent magnets 45; for example, pellicle frame 40 could be formed, inwhole or in part, of steel. The number of electromagnets used could bemore or fewer than two. Other elements utilizing magnetic fields couldalso be substituted for those shown, or they could be used to supplementthose shown.

FIG. 5 illustrates a partially exploded frontal view of yet anotherembodiment of photolithographic equipment. In this embodiment, pellicleframe 40 comprises a pair of outrigger elements 42 that extenddownwardly from pellicle frame 40. A permanent magnet 44 is provided ineach outrigger element 42. When pellicle frame 40 is positioned close tothe upper surface of photomask frame 38, the magnet 44 of each outriggerelement 42 lies immediately adjacent to a corresponding electromagnet 37of photomask frame 38.

In a manner similar to the operation of the embodiment illustrated inFIG. 4, electromagnet control unit 81 switches on electromagnets 37 whenpellicle frame 40 is overlying photomask base 32 to maintain pellicle 50over photomask base 32. When pellicle frame 40 is to be moved away fromphotomask base 32, electromagnet control unit 81 switches offelectromagnets 37. While the embodiment shown in FIG. 4 illustrateselectromagnets paired with permanent magnets, ferromagnetic materialcould be substituted for permanent magnets 44. The number ofelectromagnets used could be more or fewer than two. In addition,permanent magnets could be substituted for electromagnets. Otherelements utilizing magnetic fields could also be substituted for thoseshown, or they could be used to supplement those shown.

Alternatively, the outrigger elements 42 could extend down and beneathphotomask base 32. Or, instead of being formed on pellicle frame 40,outrigger elements 42 could be formed on photomask frame 38 or photomaskbase 32, and they could extend upwardly to be secured to suitableelements on pellicle frame 40.

The securing elements, whether in the form of permanent magnets,electromagnets, ferromagnetic material, mechanical clamps, or anothertype of securing element, could be provided on one or more sides ofpellicle frame 40, photomask frame 38, or photomask base 32; in recessesextending into or on protuberances extending from the sides of pellicleframe 40, photomask frame 38, and/or photomask base 32; on the bottomsurface of photomask base 32; on the top surface of pellicle frame 40;or any place else within the combination of elements comprising thepellicle frame 40, photomask frame 38, and photomask base 32.

FIG. 6 illustrates a partially exploded side view of the embodiment ofphotolithographic equipment illustrated in FIG. 5. Outrigger elements 42are shown on the corners of pellicle frame 40. Permanent magnets 44 orferromagnetic material located in outrigger elements 42 are magneticallyheld by electromagnets 37, when electromagnets 37 are actuated.Electromagnets 37 can be coupled by internal power cord 33.

FIG. 7 illustrates a partially exploded perspective view ofphotolithographic equipment 100 in accordance with one embodiment of theinvention. Photolithographic equipment 100 comprises photomask 102having photolithographic pattern 104.

Photolithographic equipment 100 further comprises a photomask basemember 110 aligned with photomask 102. Base member 110 can be affixed tophotomask 102, or base member 110 can merely be aligned with photomask102. Base member 110 comprises a central opening 112. In one embodiment,base member 110 further comprises a suitable securing mechanism, e.g.magnetic material or magnets 114, for securing base member 110 topellicle frame 120. Although magnets 114 are depicted as located at theupper surface of the corners of base member 110, in other embodimentsmagnets 114 could be located below the surface and/or at locations otherthan at the corners of base member 110.

Photolithographic equipment 100 additionally comprises a pellicle frame120. Pellicle frame 120 comprises a central opening 122 that can be ofequivalent dimensions to central opening 112 of base member 110.Pellicle frame 120 comprises threaded holes 128 in one of its sides.

Pellicle frame 120 can comprise a suitable securing mechanism forsecuring it to base member 110. In the embodiment shown in FIG. 7,pellicle frame 120 comprises magnets 124 arranged so their poles are ofopposite magnetic polarity to adjoining poles of magnets 114. Althoughmagnets 124 are depicted as located at the lower surface of the cornersof pellicle frame 120, in other embodiments magnets 124 could be locatedabove the surface and/or at locations other than at the corners ofpellicle frame 120. One or more magnets, such as magnets 114 and 124,could be replaced with a solenoid or electromagnet. Alternatively,magnets can be utilized on base member 110, and pellicle frame 120 couldcomprise ferromagnetic material (e.g. steel or nickel), or vice versa.

Photolithographic equipment 100 also comprises a pellicle 130 that isaffixed to pellicle frame 120. While pellicle 130 is depicted in FIG. 7as affixed to the upper surface of pellicle frame 120, it couldalternatively be affixed to the lower surface, or it could be heldwithin the central opening 122 of pellicle frame 120. Pellicle 130 canbe of any type of material, such as those materials mentioned earlier.

Photolithographic equipment 100 further comprises transport unit 140which can be of similar type to transport unit 70 described earlier.Transport unit 140 comprises robot arm 142, which comprises a cross-bar144 and fasteners 148. Fasteners 148 can be of any suitable type, suchas screws, bolts, and the like. Fasteners 148 mate with threaded holes128 in the side of pellicle frame 120.

Transport unit 140 also comprises a slot 146 to permit robot arm 142 tomove pellicle frame 120 off base member 110 and to rotate pellicle frame120 away from base member 110, when photomask 102 is subjected tophotolithographic radiation during exposure, or to allow physical accessto photomask 102. Other types of transport mechanisms could besubstituted for transport unit 140. For example, pellicle frame 120could be elevated to sufficient height to allow access to photomask 102.

Together, the various elements making up the pellicle device, namelyphotomask base 110, pellicle frame 120, and pellicle 130, form aprotective enclosure around photomask 102 to protect photomask 102 fromsources of contaminants such as particles.

FIG. 8 illustrates a top view of the embodiment of photolithographicequipment 100 illustrated in FIG. 7. In FIG. 8, pellicle 130 isillustrated in two different positions. In a first position, pellicle130 overlies base member 110 (refer to FIG. 7). In a second position,pellicle 130 has been elevated by robot arm 142 of transport unit 140,and then it has been moved or rotated 90 degrees about a vertical axisin the direction indicated by dashed arrow 147, so that pellicle 130does not overlie base member 110. Pellicle 130 could also have beenrotated another 90 degrees in the direction indicated by dashed arrow149, in order to further move pellicle 130 away from photomask 102, forexample to facilitate cleaning or replacement of photomask 102.

FIG. 9 illustrates a perspective view of photolithographic equipment 200in accordance with one embodiment of the invention. Photolithographicequipment 200 comprises pellicle frame 220, which in turn comprisespellicle elements in the form of shutters 222 and 224. Shutters 222 and224, when in their closed positions, completely cover thephotolithographic pattern 208 of photomask 206 that appears withinaperture 204 in pellicle frame 220. In FIG. 9, shutter 222 is shown in aclosed position, in which it overlies and covers photomask 206, whileshutter 224 is shown in an open position away from photomask 206.

Shutters 222 and 224 can be moved by any suitable transport mechanism.In the embodiment illustrated in FIG. 9, shutters 222 and 224 comprisecontrol rods 232 and 236, respectively. A transport unit 210 comprises atransport rod 234 that is coupled to control rod 232 of shutter 222 viaa coupler 233. Similarly, transport unit 212 comprises a transport rod238 that is coupled to control rod 236 of shutter 224 via a coupler 237.Transport units 210 and 212 open and close shutters 222 and 224,respectively, through suitable movement of transport rods 234 and 238.

While in the embodiment illustrated in FIG. 9, transport units 210 and212 can independently control the movement of shutters 222 and 224, inanother embodiment, they operate in synchronism to open and closeshutters 222 and 224. In yet another embodiment, only one transport unitis provided to open and close shutters 222 and 224. In a furtherembodiment, more or fewer than two shutters are used. Other types oftransport mechanisms could also be used.

FIG. 10 illustrates a cross-sectional view of photolithographicequipment 200 taken along line 201 of FIG. 9. Shutter 222 rests upon andmoves back and forth upon shelf 242, while shutter 224 rests upon andmoves upon shelf 244. In another embodiment, shutters 222 and 224 eachmove within respective retention brackets (not shown) that are coupledto the interior of pellicle frame 220. Photomask 206 lies upon photomasksubstrate or base 218. Pellicle frame 220, shutters 222 and 224, andphotomask base 218 form a protective enclosure around photomask 206 toprotect photomask 206 from sources of optical contaminants such asparticles.

FIG. 11 illustrates a perspective view of photolithographic equipment300 in accordance with one embodiment of the invention.Photolithographic equipment 300 comprises pellicle enclosure 320, whichin turn comprises pellicle elements in the form of shutters 322 and 324.Shutters 322 and 324, when in their closed positions, completely coverand protect the photolithographic pattern 308 of photomask 306 thatappears within aperture 304 in pellicle enclosure 320. In FIG. 11,shutter 322 is shown in a closed position, in which it overlies andcovers photomask 306, while shutter 324 is shown in an open positionaway from photomask 306.

Shutters 322 and 324 can be moved by any suitable transport mechanism.In the embodiment illustrated in FIG. 11, shutter 322 is coupled to afirst articulated arm comprising arm segments 342 and 343, and to asecond articulated arm comprising arm segments 352 and 353. Arm segments342 and 352 are in turn coupled to a transport axle 314 through openings326 and 327, respectively, of a transport unit 310. When transport axle314 is rotated by transport unit 310, the articulated arms open or closeshutter 322.

Similarly, shutter 324 is coupled to a first articulated arm member orarm comprising arm segments 344 and 345, and to a second articulated armcomprising arm segments 354 and 355. Arm segments 344 and 354 are inturn coupled to a transport axle 316 through openings 328 and 329,respectively, of a transport unit 312. When transport axle 316 isrotated by transport unit 312, the articulated arms open or closeshutter 324.

While in the embodiment illustrated in FIG. 11, transport units 310 and312 can independently control the movement of shutters 322 and 324, inanother embodiment, they operate in synchronism to open and closeshutters 322 and 324. In yet another embodiment, only one transport unitis provided to open and close shutters 322 and 324. In a furtherembodiment, more or fewer than two shutters are used. Other types oftransport mechanisms could also be used.

FIG. 12 illustrates a cross-sectional view of photolithographicequipment 300 taken along line 301 of FIG. 1. Photomask 306 lies uponphotomask substrate or base 318. Pellicle enclosure 320, includingshutters 322 and 324, forms a protective enclosure around photomask 306to protect photomask 306 from sources of contaminants such as particles.

FIG. 13 illustrates a perspective view of photolithographic equipment400 in accordance with one embodiment of the invention.Photolithographic equipment 400 comprises pellicle support 420, which inturn comprises a pellicle in the form of a pellicle diaphragm 430.Pellicle diaphragm 430 comprises a plurality of diaphragm elements oroverlapping shutter leaves 428 that can open or close. Pelliclediaphragm 430, when in its closed position, completely covers andprotects the photolithographic pattern 408 of photomask 406 that appearswithin aperture 432 in pellicle diaphragm 420. In FIG. 13, pelliclediaphragm 430 is shown in a partially open position, in which itpartially overlies and covers photomask 406.

Pellicle diaphragm 430 can be open and closed by any suitable transportmechanism. In the embodiment illustrated in FIG. 13, pellicle diaphragm430 is coupled to a pair of transport arms 434 and 436. Transport arms434 and 436 are in turn controlled and moved by transport units 410 and412, respectively. Transport unit 410 is structurally coupled tophotomask base 418 (FIG. 14) through structural elements 414 and 424.Similarly, transport unit 412 is structurally coupled to photomask base418 (FIG. 14) through structural elements 416 and 426.

While in the embodiment illustrated in FIG. 13, transport units 410 and412 together control the movement of pellicle diaphragm 430, in anotherembodiment only one transport unit is provided to open and closepellicle diaphragm 430. Other types of transport mechanisms could alsobe used.

FIG. 14 illustrates a cross-sectional view of photolithographicequipment 400 taken along line 401 of FIG. 13. Photomask 406 lies uponphotomask substrate or base 418. Pellicle support 420, includingpellicle diaphragm 430, forms a protective enclosure around photomask406 to protect photomask 406 from sources of contaminants such asparticles.

FIG. 15 illustrates a flow diagram of a method 500 of using aretractable pellicle, in accordance with one embodiment of theinvention. In 502, a photomask is covered with a retractable pellicle.In 504, the pellicle is pivotlessly retracted away from the photomask touncover the photomask, e.g. when irradiating the photomask withphotolithographic radiation, or when accessing the photomask for anypurpose, such as to clean or remove it. In one embodiment, thewavelength of the photolithographic radiation is in the range of 2–200nanometers; however, the invention is not limited to this range ofwavelengths. The photolithographic radiation is typically from the groupconsisting of ultraviolet, deep ultraviolet, extreme ultraviolet, X-ray,electron beam, and ion beam radiation; however, the invention could alsobe practiced with radiation from the visible spectrum. In 506, thepellicle is replaced when not irradiating the photomask withphotolithographic radiation, or when not accessing the photomask, inorder to protect the photomask from optical contamination, such asparticles. The method ends at 508.

FIG. 16 illustrates a flow diagram of a method 520 of using a pivotablepellicle, in accordance with one embodiment of the invention. In 522, aphotomask is covered with a pellicle that is pivotable about a verticalaxis. In 524, the pellicle is pivoted away from the photomask to uncoverthe photomask, e.g. when irradiating the photomask withphotolithographic radiation, or when accessing the photomask. In 526,the pellicle is replaced when not irradiating the photomask withphotolithographic radiation, or when not accessing the photomask, inorder to protect the photomask from optical contamination. The methodends at 528.

FIG. 17 illustrates a flow diagram of a method 540 of using a pelliclecomprising two or more shutters, in accordance with one embodiment ofthe invention. In 540, a photomask is covered with a pellicle comprisingtwo or more shutters. In 544, the pellicle shutters are opened touncover the photomask, e.g. when irradiating the photomask withphotolithographic radiation, or when accessing the photomask. In 546,the pellicle shutters are closed when not irradiating the photomask withphotolithographic radiation, or when not accessing the photomask, inorder to protect the photomask from optical contamination. The methodends at 548.

FIG. 18 illustrates a flow diagram of a method 560 of using a pelliclecomprising a diaphragm, in accordance with one embodiment of theinvention. In 560, a photomask is covered with a pellicle comprising adiaphragm. In 564, the pellicle diaphragm is opened to uncover thephotomask, e.g. when irradiating the photomask with photolithographicradiation, or when accessing the photomask. In 566, the pelliclediaphragm is closed when not irradiating the photomask withphotolithographic radiation, or when not accessing the photomask, inorder to protect the photomask from optical contamination. The methodends at 568.

As mentioned above, in addition, or alternatively, to moving and/oropening the pellicle during exposure of the photomask, the pellicle canbe moved and/or opened when it is desired to access the photomask or anyelements associated therewith, such as for the purpose of cleaning orinspecting the photomask or for other purposes.

Although FIGS. 15–18 depict the methods as having an “end”, it will beunderstood that the methods can be indefinitely repeated.

The present invention provides for apparatus and methods that permit theuse of pellicles for photolithographic operations using actinicradiation and/or radiation beyond the visible light spectrum. Byemploying a movable and/or removable pellicle, the pellicle is notdamaged by the photolithographic radiation. In addition, the pelliclecan readily be moved and/or removed when it is necessary to access thephotomask. In addition, the pellicle can be readily replaced withoutdamaging the photomask. As a result, the invention reduces semiconductorproduction costs and enables semiconductors to be marketed morecompetitively and with higher quality than with known apparatus andmethods for performing semiconductor photolithography.

As shown herein, the present invention can be implemented in a number ofdifferent embodiments, including but not limited to a pellicle devicehaving a pellicle that retracts, slides, or pivots with respect to aphotomask; to a pellicle device having a pellicle in the form of adiaphragm or one or more shutters that open and close; and to variousmethods for using a pellicle. Other embodiments will be readily apparentto those of ordinary skill in the art. For example, the invention couldbe used with photolithographic radiation within the visible spectrum.

The architecture, composition, materials, dimensions, and sequence ofoperations can all be varied to suit particular requirements ofsemiconductor photolithographic environments.

The various elements depicted in the drawings are merelyrepresentational and are not drawn to scale. Certain proportions thereofmay be exaggerated, while others may be minimized. The drawings areintended to illustrate various implementations of the invention, whichcan be understood and appropriately carried out by those of ordinaryskill in the art.

Although specific embodiments have been illustrated and describedherein, it will be appreciated by those of ordinary skill in the artthat any arrangement that is calculated to achieve the same purpose maybe substituted for the specific embodiment shown. This application isintended to cover any adaptations or variations of the inventive subjectmatter. Therefore, it is manifestly intended that embodiments of thisinvention be limited only by the claims and the equivalents thereof.

1. A pellicle device comprising: a base to align with a photomask, thephotomask having a surface; a pellicle to slide relative to the basebetween a first position overlying the photomask and a second positionnot overlying the photomask; and a transport element to move thepellicle between the first and second positions in a direction parallelto the surface of the photomask.
 2. The pellicle device of claim 1,wherein the pellicle comprises at least one shutter to open and close.3. The pellicle device of claim 1, wherein the pellicle comprises asecuring mechanism to maintain the pellicle overlying the base when thepellicle is in the first position.
 4. The pellicle device of claim 3,wherein the securing mechanism uses at least one magnetic field.
 5. Thepellicle device of claim 4, wherein the securing mechanism comprises anelectromagnet to produce the at least one magnetic field.
 6. Thepellicle device of claim 4, wherein the securing mechanism furthercomprises an outrigger element within the at least one magnetic field.7. A pellicle device comprising: a base to align with a photomask, thephotomask having a surface; a pellicle to move pivotlessly relative tothe base between a first position overlying the photomask and a secondposition not overlying the photomask; and a transport element to movethe pellicle between the first and second positions in a directionparallel to the surface of the photomask.
 8. The pellicle device ofclaim 7, wherein the transport element comprises at least one arm membercoupled to the pellicle.
 9. The pellicle device of claim 7, wherein thepellicle does not contact the base in the second position.
 10. Thepellicle device of claim 7, wherein the pellicle comprises at least oneshutter to open and close.
 11. The pellicle device of claim 7, whereinthe pellicle comprises a securing mechanism to maintain the pellicleoverlying the base when the pellicle is in the first position.
 12. Thepellicle device of claim 7, wherein the pellicle is opaque tophotolithographic radiation.
 13. The pellicle device of claim 7, whereina portion of the pellicle is transparent to inspection radiation.
 14. Apellicle device comprising: a base to align with a photomask; a pellicleto move along a vertical axis relative to the base between a firstposition overlying the photomask and an intermediate position off thebase, and to rotate about the vertical axis between the intermediateposition and a second position not overlying the photomask; and anelectro-mechanical transport element to move the pellicle between thefirst and second positions.
 15. The pellicle device of claim 14, whereinthe pellicle comprises a securing mechanism to maintain the pellicleoverlying the base when the pellicle is in the first position.
 16. Thepellicle device of claim 15, wherein the securing mechanism uses atleast one magnetic field.
 17. A pellicle device comprising: a base toalign with a photomask; a pellicle diaphragm comprising at least threeoverlapping shutter leaves, coupled to the base, the shutter leaveshaving a closed position to cover the photomask and the shutter leaveshaving an open position to uncover the photomask.
 18. The pellicledevice of claim 17, wherein the pellicle device further comprises atransport element coupled to the pellicle diaphragm to open and closethe pellicle diaphragm.
 19. The pellicle device of claim 17, wherein thebase and the pellicle diaphragm form a protective enclosure around thephotomask.
 20. A method comprising: covering a photomask with apellicle, the photomask having a surface, and the pellicle comprising apair of shutters; and pivotlessly retracting the pellicle shutters awayfrom the photomask in opposing directions that are parallel to thesurface of the photomask to uncover the photomask.
 21. The methodrecited in claim 20, wherein the pellicle is retracted to irradiate thephotomask with photolithographic radiation.
 22. The method recited inclaim 21 and further comprising: replacing the pellicle to cover thephotomask when not irradiating the photomask with photolithographicradiation.
 23. The method recited in claim 22, wherein the pellicle iscoupled to a transport element, the method further comprising:retracting and replacing the pellicle using the transport element. 24.The method recited in claim 20, wherein the wavelength of thephotolithographic radiation is within the range of 2 to 200 nanometers.25. The method recited in claim 20, wherein the photolithographicradiation is from the group consisting of ultraviolet, deep ultraviolet,extreme ultraviolet, X-ray, electron beam, and ion beam.
 26. A methodcomprising: covering a photomask with a pellicle, the pellicle beingmoveable along and pivotable about a vertical axis that is perpendicularto a surface of the photomask; moving the pellicle along the verticalaxis away from the photomask to partially uncover the photomask; andpivoting the pellicle about the vertical axis away from the photomask tofully uncover the photomask.
 27. The method recited in claim 26, whereinthe photomask is uncovered to irradiate the photomask withphotolithographic radiation.
 28. The method recited in claim 26 andfurther comprising: replacing the pellicle to cover the photomask whennot irradiating the photomask with photolithographic radiation.
 29. Themethod recited in claim 26, wherein the pellicle is coupled to atransport element, the method further comprising: pivoting and replacingthe pellicle using the transport element.
 30. A method comprising:covering a photomask with a pellicle comprising a diaphragm having aplurality of shutter leaves; and opening the diaphragm shutter leaves touncover the photomask.
 31. The method recited in claim 30, wherein thephotomask is uncovered to irradiate the photomask with photolithographicradiation.
 32. The method recited in claim 30 and further comprising:closing the diaphragm shutter leaves when not irradiating the photomaskwith photolithographic radiation.
 33. The method recited in claim 30,wherein the diaphragm is coupled to a transport element, the methodfurther comprising: opening and closing the diaphragm shutter leaveswith the transport element.
 34. A method comprising: covering aphotomask with a pellicle, the photomask having a surface, and thepellicle comprising a pair of shutters; and pivoting each of thepellicle shutters about an axis parallel to the photomask surface touncover the photomask.
 35. The method recited in claim 34, wherein thephotomask is uncovered to irradiate the photomask with photolithographicradiation.
 36. The method recited in claim 34 and further comprising:replacing the pellicle to cover the photomask when not irradiating thephotomask with photolithographic radiation.
 37. The method recited inclaim 34, wherein the pellicle is coupled to a transport element, themethod further comprising: pivoting and replacing the pellicle shuttersusing the transport element.